The major objective has been to evaluate methyl acetimidate as a potential extracorporeal agent for the treatment of sickle cell anemia. Both biochemical and cellular studies of lysate obtained from methyl acetimidate incubated erythrocytes have been performed to determine the extent of the reaction with hemoglobin and to determine whether the reaction has any adverse effects on the treated erythrocytes. We have shown that methyl acetimidate prevents sickling both by chemical modification of hemoglobin S so that the sickle gel is destabilized, and by increasing the oxygen affinity of the modified hemoglobin. We have also shown that the in vitro incubation of erythrocytes with methyl acetimidate does not have any serious adverse effects on the incubated cells. It is concluded that methyl acetimidate may serve as an effective extracorporeal agent for the treatment of sickle cell anemia. The goals for the coming year are to continue to study the effects of the methyl acetimidate incubation on the physiological properties of the modified hemoglobin. Both the oxygen affinity of incubated cells and modified hemoglobin obtained from the modified erythrocytes will be determined as a function of the imidate concentration, pH, temperature, and state of ligation of hemoglobin. The effect of 2,3-diphosphoglycerate and inositol hexaphosphate on the oxygen affinity and the reaction itself will also be studied.